This invention relates to a synthetic resin bottle, which is provided with plural panels used to absorb the changes in inner pressure created inside the bottle.
What is called the hot filling process is used to fill a polyethylene terephthalate resin (hereinafter referred to as PET resin) bottle with contents, such as fruit juices, teas, and the like, for which sterilization is required. It involves filling the bottle with the contents at a temperature of about 90 degrees Centigrade, sealing the bottle with a cap, and cooling the capped bottle. Inside of the bottle turns out to be under a considerably reduced pressure condition.
Therefore, the so-called depressurization-absorbing panels are formed on purpose on the body wall for those uses that involve the hot filling process described above. These panels occupy the areas in which the panel walls are easily deformable into a dented shape when bottle inside is under reduced pressure. Because only the panels are made to get dented under reduced pressure, the bottle itself retains good appearance, and the portions other than the panels have sufficient rigidity as a bottle. Therefore, the bottles have no trouble on the bottle transport lines, in the stacked bottle storage, and inside the automatic vending machines.
Patent Document 1, for example, has the descriptions of a bottle provided with depressurization-absorbing panels. FIG. 13 shows a bottle illustrated in an embodiment of Patent Document 1. This bottle 101 is a cylindrical PET bottle with a capacity of 500 ml, and comprises a neck 102, a shoulder 103, a body 104, a bottom 105, and an encircling groove 106 at bout mid-height. Six depressurization-absorbing panels 107 are formed below this encircling groove 106. The panels 107 are roughly flat in their shape, and are easily deformable into a dented shape when the inside of the bottle 101 is under reduced pressure. Because of these panels 107, the bottle 101 in its appearance gives no impression of a distorted shape, and fulfills the function of absorbing or relieving inconspicuously depressurization (hereinafter referred to as the depressurization-absorbing function). Support pillars 109 are formed between adjacent depressurization-absorbing panels 107 to retain the rigidity of the bottle.
Vertical ribs 108 are shown in a dented shape in FIG. 13, but these ribs may have a projecting shape. However, in the case of dented ribs, thicker walls are obtained for each connecting part between a vertical rib 108 and a vacuum absorbing panel 107 than in the case of projecting ribs, and thus the dented ribs ensure that the support pillars 109 are prevented from deformation.
[Patent Document 1] P1998-58527
In recent years, synthetic resin bottles, such as the PET resin bottles described above, have been in much use for the foods requiring retort treatment in packaging. In such cases, the retort treatment is carried out by filling the bottle with a food at a temperature in the range of room temperature to 80 degrees C. and by utilizing pressurized hot water or heating steam to heat-sterilize the food at a temperature of 120-130 degrees C. for about 20 min in a retort kettle or autoclave in the state in which the neck has been sealed with a cap.
In summer, the above-described synthetic resin bottles, such as PET resin bottles, may also be put in the freezer to enjoy ice-cold drinks as the frozen contents are gradually melted up.